Fix/Freeze/Clamp Object Info at certain value
You can use "baking" for this. Colors can be written on image texture.

1) First, setup UV for all objects. Select all objects, press Space and search for "Smart UV Project".

2) Next, connect what you want to bake to emission shader. Add an image texture and put it on node setup like this:



3) Find "Bake" section in render settings, select type to "emit" and press "Bake"



4) If you will do everything right you will get an image like this, save it.



5) Finally, connect image node to your node setup